The future gateway cable modem (CM) will provide a wide range of data networking and VoIP services, as exemplified by the requirements for initiatives such as CableHome and PacketCable. The major challenge in designing such a gateway cable modem is integration of these services with the basic cable modem functionality in an efficient and cost-effective. Several objectives need to be met:
Functional Partitioning. The gateway cable modem will incorporate a variety of functions beyond the traditional cable modem, including IP routing, network address translation (NAT)/firewall, virtual private network (VPN), web server and VoIP. These functions need to utilize DOCSIS (Data Over Cable Service Interface Specification)services (link-layer transport and QoS) for wide area network (WAN) access. Partitioning these functions along with other cable modem functions among different computational agents is an essential issue in designing a gateway cable modem.
Flexiblity. The architecture of the gateway cable modem should be flexible enough to allow independent software development and field-upgrade of gateway value-added services and basic DOCSIS cable modem services. From a development standpoint, the architecture should facilitate different software-partnering models, including all in-house, software components licensing, and OEM vendor-differentiating design. From a multiple system operator (MSO) perspective, it is highly desirable to be able to independently provision, maintain and upgrade revenue-producing gateway services and basic broadband access services.
Performance. The gateway cable modem should be able to support a large number of simultaneous data application sessions originated from/terminated on multiple CPE (customer provided equipment) devices. VoIP applications must not be adversely impacted by an concurrent data applications, and the data path for voice packets must be optimized to minimize delay and jitter.
Cost. The gateway cable modem chip should have a small incremental hardware cost/functional increase relative to stand-alone cable modem chips.
Software Re-Use. It should be possible to carry over existing cable modem software to the new gateway cable modem without major changes. The existing software running on network processors should be easily portable to run on the gateway platform without major adaptation.
The present invention provides a gateway cable modem architecture that meets all of these objectives.